4 * Copyright (C) 2013 Proxmox Server Solutions
5 * Copyright (c) 2019 Virtuozzo International GmbH.
8 * Dietmar Maurer (dietmar@proxmox.com)
10 * This work is licensed under the terms of the GNU GPL, version 2 or later.
11 * See the COPYING file in the top-level directory.
15 #include "qemu/osdep.h"
18 #include "block/block.h"
19 #include "block/block_int.h"
20 #include "block/blockjob_int.h"
21 #include "block/block_backup.h"
22 #include "block/block-copy.h"
23 #include "qapi/error.h"
24 #include "qapi/qmp/qerror.h"
25 #include "qemu/ratelimit.h"
26 #include "qemu/cutils.h"
27 #include "sysemu/block-backend.h"
28 #include "qemu/bitmap.h"
29 #include "qemu/error-report.h"
31 #include "block/backup-top.h"
33 #define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
35 typedef struct BackupBlockJob {
37 BlockDriverState *backup_top;
38 BlockDriverState *source_bs;
40 BdrvDirtyBitmap *sync_bitmap;
42 MirrorSyncMode sync_mode;
43 BitmapSyncMode bitmap_mode;
44 BlockdevOnError on_source_error;
45 BlockdevOnError on_target_error;
54 static const BlockJobDriver backup_job_driver;
56 static void backup_progress_bytes_callback(int64_t bytes, void *opaque)
58 BackupBlockJob *s = opaque;
60 s->bytes_read += bytes;
63 static int coroutine_fn backup_do_cow(BackupBlockJob *job,
64 int64_t offset, uint64_t bytes,
68 int64_t start, end; /* bytes */
70 start = QEMU_ALIGN_DOWN(offset, job->cluster_size);
71 end = QEMU_ALIGN_UP(bytes + offset, job->cluster_size);
73 trace_backup_do_cow_enter(job, start, offset, bytes);
75 ret = block_copy(job->bcs, start, end - start, true, error_is_read);
77 trace_backup_do_cow_return(job, offset, bytes, ret);
82 static void backup_cleanup_sync_bitmap(BackupBlockJob *job, int ret)
85 bool sync = (((ret == 0) || (job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS)) \
86 && (job->bitmap_mode != BITMAP_SYNC_MODE_NEVER));
90 * We succeeded, or we always intended to sync the bitmap.
91 * Delete this bitmap and install the child.
93 bm = bdrv_dirty_bitmap_abdicate(job->sync_bitmap, NULL);
96 * We failed, or we never intended to sync the bitmap anyway.
97 * Merge the successor back into the parent, keeping all data.
99 bm = bdrv_reclaim_dirty_bitmap(job->sync_bitmap, NULL);
104 if (ret < 0 && job->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS) {
105 /* If we failed and synced, merge in the bits we didn't copy: */
106 bdrv_dirty_bitmap_merge_internal(bm, block_copy_dirty_bitmap(job->bcs),
111 static void backup_commit(Job *job)
113 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
114 if (s->sync_bitmap) {
115 backup_cleanup_sync_bitmap(s, 0);
119 static void backup_abort(Job *job)
121 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
122 if (s->sync_bitmap) {
123 backup_cleanup_sync_bitmap(s, -1);
127 static void backup_clean(Job *job)
129 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
130 bdrv_backup_top_drop(s->backup_top);
133 void backup_do_checkpoint(BlockJob *job, Error **errp)
135 BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
137 assert(block_job_driver(job) == &backup_job_driver);
139 if (backup_job->sync_mode != MIRROR_SYNC_MODE_NONE) {
140 error_setg(errp, "The backup job only supports block checkpoint in"
145 bdrv_set_dirty_bitmap(block_copy_dirty_bitmap(backup_job->bcs), 0,
149 static BlockErrorAction backup_error_action(BackupBlockJob *job,
150 bool read, int error)
153 return block_job_error_action(&job->common, job->on_source_error,
156 return block_job_error_action(&job->common, job->on_target_error,
161 static bool coroutine_fn yield_and_check(BackupBlockJob *job)
165 if (job_is_cancelled(&job->common.job)) {
170 * We need to yield even for delay_ns = 0 so that bdrv_drain_all() can
171 * return. Without a yield, the VM would not reboot.
173 delay_ns = block_job_ratelimit_get_delay(&job->common, job->bytes_read);
175 job_sleep_ns(&job->common.job, delay_ns);
177 if (job_is_cancelled(&job->common.job)) {
184 static int coroutine_fn backup_loop(BackupBlockJob *job)
188 BdrvDirtyBitmapIter *bdbi;
191 bdbi = bdrv_dirty_iter_new(block_copy_dirty_bitmap(job->bcs));
192 while ((offset = bdrv_dirty_iter_next(bdbi)) != -1) {
194 if (yield_and_check(job)) {
197 ret = backup_do_cow(job, offset, job->cluster_size, &error_is_read);
198 if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
199 BLOCK_ERROR_ACTION_REPORT)
207 bdrv_dirty_iter_free(bdbi);
211 static void backup_init_bcs_bitmap(BackupBlockJob *job)
215 BdrvDirtyBitmap *bcs_bitmap = block_copy_dirty_bitmap(job->bcs);
217 if (job->sync_mode == MIRROR_SYNC_MODE_BITMAP) {
218 ret = bdrv_dirty_bitmap_merge_internal(bcs_bitmap, job->sync_bitmap,
222 if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
224 * We can't hog the coroutine to initialize this thoroughly.
225 * Set a flag and resume work when we are able to yield safely.
227 block_copy_set_skip_unallocated(job->bcs, true);
229 bdrv_set_dirty_bitmap(bcs_bitmap, 0, job->len);
232 estimate = bdrv_get_dirty_count(bcs_bitmap);
233 job_progress_set_remaining(&job->common.job, estimate);
236 static int coroutine_fn backup_run(Job *job, Error **errp)
238 BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
241 backup_init_bcs_bitmap(s);
243 if (s->sync_mode == MIRROR_SYNC_MODE_TOP) {
247 for (offset = 0; offset < s->len; ) {
248 if (yield_and_check(s)) {
252 ret = block_copy_reset_unallocated(s->bcs, offset, &count);
259 block_copy_set_skip_unallocated(s->bcs, false);
262 if (s->sync_mode == MIRROR_SYNC_MODE_NONE) {
264 * All bits are set in bcs bitmap to allow any cluster to be copied.
265 * This does not actually require them to be copied.
267 while (!job_is_cancelled(job)) {
269 * Yield until the job is cancelled. We just let our before_write
270 * notify callback service CoW requests.
275 return backup_loop(s);
281 static const BlockJobDriver backup_job_driver = {
283 .instance_size = sizeof(BackupBlockJob),
284 .job_type = JOB_TYPE_BACKUP,
285 .free = block_job_free,
286 .user_resume = block_job_user_resume,
288 .commit = backup_commit,
289 .abort = backup_abort,
290 .clean = backup_clean,
294 static int64_t backup_calculate_cluster_size(BlockDriverState *target,
299 bool target_does_cow = bdrv_backing_chain_next(target);
302 * If there is no backing file on the target, we cannot rely on COW if our
303 * backup cluster size is smaller than the target cluster size. Even for
304 * targets with a backing file, try to avoid COW if possible.
306 ret = bdrv_get_info(target, &bdi);
307 if (ret == -ENOTSUP && !target_does_cow) {
308 /* Cluster size is not defined */
309 warn_report("The target block device doesn't provide "
310 "information about the block size and it doesn't have a "
311 "backing file. The default block size of %u bytes is "
312 "used. If the actual block size of the target exceeds "
313 "this default, the backup may be unusable",
314 BACKUP_CLUSTER_SIZE_DEFAULT);
315 return BACKUP_CLUSTER_SIZE_DEFAULT;
316 } else if (ret < 0 && !target_does_cow) {
317 error_setg_errno(errp, -ret,
318 "Couldn't determine the cluster size of the target image, "
319 "which has no backing file");
320 error_append_hint(errp,
321 "Aborting, since this may create an unusable destination image\n");
323 } else if (ret < 0 && target_does_cow) {
324 /* Not fatal; just trudge on ahead. */
325 return BACKUP_CLUSTER_SIZE_DEFAULT;
328 return MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
331 BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
332 BlockDriverState *target, int64_t speed,
333 MirrorSyncMode sync_mode, BdrvDirtyBitmap *sync_bitmap,
334 BitmapSyncMode bitmap_mode,
336 const char *filter_node_name,
338 BlockdevOnError on_source_error,
339 BlockdevOnError on_target_error,
341 BlockCompletionFunc *cb, void *opaque,
342 JobTxn *txn, Error **errp)
344 int64_t len, target_len;
345 BackupBlockJob *job = NULL;
346 int64_t cluster_size;
347 BdrvRequestFlags write_flags;
348 BlockDriverState *backup_top = NULL;
349 BlockCopyState *bcs = NULL;
354 /* QMP interface protects us from these cases */
355 assert(sync_mode != MIRROR_SYNC_MODE_INCREMENTAL);
356 assert(sync_bitmap || sync_mode != MIRROR_SYNC_MODE_BITMAP);
359 error_setg(errp, "Source and target cannot be the same");
363 if (!bdrv_is_inserted(bs)) {
364 error_setg(errp, "Device is not inserted: %s",
365 bdrv_get_device_name(bs));
369 if (!bdrv_is_inserted(target)) {
370 error_setg(errp, "Device is not inserted: %s",
371 bdrv_get_device_name(target));
375 if (compress && !bdrv_supports_compressed_writes(target)) {
376 error_setg(errp, "Compression is not supported for this drive %s",
377 bdrv_get_device_name(target));
381 if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
385 if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
389 cluster_size = backup_calculate_cluster_size(target, errp);
390 if (cluster_size < 0) {
394 if (perf->max_workers < 1) {
395 error_setg(errp, "max-workers must be greater than zero");
399 if (perf->max_chunk < 0) {
400 error_setg(errp, "max-chunk must be zero (which means no limit) or "
405 if (perf->max_chunk && perf->max_chunk < cluster_size) {
406 error_setg(errp, "Required max-chunk (%" PRIi64 ") is less than backup "
407 "cluster size (%" PRIi64 ")", perf->max_chunk, cluster_size);
413 /* If we need to write to this bitmap, check that we can: */
414 if (bitmap_mode != BITMAP_SYNC_MODE_NEVER &&
415 bdrv_dirty_bitmap_check(sync_bitmap, BDRV_BITMAP_DEFAULT, errp)) {
419 /* Create a new bitmap, and freeze/disable this one. */
420 if (bdrv_dirty_bitmap_create_successor(sync_bitmap, errp) < 0) {
425 len = bdrv_getlength(bs);
427 error_setg_errno(errp, -len, "Unable to get length for '%s'",
428 bdrv_get_device_or_node_name(bs));
432 target_len = bdrv_getlength(target);
433 if (target_len < 0) {
434 error_setg_errno(errp, -target_len, "Unable to get length for '%s'",
435 bdrv_get_device_or_node_name(bs));
439 if (target_len != len) {
440 error_setg(errp, "Source and target image have different sizes");
445 * If source is in backing chain of target assume that target is going to be
446 * used for "image fleecing", i.e. it should represent a kind of snapshot of
447 * source at backup-start point in time. And target is going to be read by
448 * somebody (for example, used as NBD export) during backup job.
450 * In this case, we need to add BDRV_REQ_SERIALISING write flag to avoid
451 * intersection of backup writes and third party reads from target,
452 * otherwise reading from target we may occasionally read already updated by
455 * For more information see commit f8d59dfb40bb and test
456 * tests/qemu-iotests/222
458 write_flags = (bdrv_chain_contains(target, bs) ? BDRV_REQ_SERIALISING : 0) |
459 (compress ? BDRV_REQ_WRITE_COMPRESSED : 0),
461 backup_top = bdrv_backup_top_append(bs, target, filter_node_name,
463 write_flags, &bcs, errp);
468 /* job->len is fixed, so we can't allow resize */
469 job = block_job_create(job_id, &backup_job_driver, txn, backup_top,
471 speed, creation_flags, cb, opaque, errp);
476 job->backup_top = backup_top;
478 job->on_source_error = on_source_error;
479 job->on_target_error = on_target_error;
480 job->sync_mode = sync_mode;
481 job->sync_bitmap = sync_bitmap;
482 job->bitmap_mode = bitmap_mode;
484 job->cluster_size = cluster_size;
488 block_copy_set_progress_callback(bcs, backup_progress_bytes_callback, job);
489 block_copy_set_progress_meter(bcs, &job->common.job.progress);
491 /* Required permissions are already taken by backup-top target */
492 block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,
499 bdrv_reclaim_dirty_bitmap(sync_bitmap, NULL);
502 bdrv_backup_top_drop(backup_top);